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Introduction: Photoelectrochemical Cells and Donor / Acceptor Hybrids Right: Photoelectrochemical cells isolate charge carrier generation and transport, unlike conventional solid state doped silicon devices. – Dye sensitized solar cells (DSSC) can reach overall efficiencies up to 11%, at a fraction of cost of conventional Si devices. – Typically, a nanocrystalline TiO 2 is used as a semiconducting layer on ITO, covered with a ruthenium based dye, which donates photoexcited electron into TiO 2 where charge separation takes place. The porous structure TiO 2 allows for large amount of dye molecules per unit area, but can have recombination due to poor diffusion of excited electrons. At the foundation is the interactions of donor / acceptor hybrids, where a molecular donor with ideal optical properties donates excited electron to an acceptor, slowing charge recombination and transporting charge to electrodes.